1. Field of the Invention
The present invention relates to an electronic apparatus comprising a main micro processor and an auxiliary micro processor and controlling an electric power supply to the main micro processor and peripheral devices through the auxiliary micro processor.
2. Description of the Related Art
With regard to an electronic apparatus such as a DVD recorder comprising a main micro processor and an auxiliary micro processor, it is conventionally known that the auxiliary micro processor controls electric power supply to the main micro processor and peripheral devices. In such an electronic apparatus, a program and data relating to a power control method for controlling the electric power supply are stored in a mask ROM (Read Only Memory) in the auxiliary micro processor, and the auxiliary micro processor controls the electric power supply to the main micro processor and the peripheral devices based on the program and the data stored in its own mask ROM.
Japanese Laid-Open Patent Publication No. 4-333119 discloses an electronic apparatus that a power control circuit is monitored and controlled with a sub-CPU and a power source of a device not in use is switched off with an input-output device. Japanese Laid-Open Patent Publication No. 10-049265 discloses an electronic apparatus that a sub-CPU switches off a power source of an I/O device by compulsion when receiving an order from a main CPU. Japanese Laid-Open Patent Publication No. 64-012321 discloses an electronic apparatus that a system power control unit composed of a one-chip microcomputer is mounted separately from a main CPU and a calendar updating and a power control are operated by the system power control unit in isolation from the main-CPU.
However, with regard to the conventional electronic apparatuses described above, since the auxiliary micro processor is constituted to have a mask ROM system, a program and data regarding a power control method stored in the mask ROM of the auxiliary micro processor cannot be rewritten. For this reason, in case that the power control method needs to be changed due to a problem that a main micro processor and peripheral devices do not function well when a power source is supplied to them, the auxiliary micro processor having the mask ROM system has to be remade every time, thus a problem such as a delay of a due date or a cost increase arises.